Keyboard mechanism for teletypewriters



June 30, 1953 D. E. BRANSON KEYBOARD MECHANISM FOR TELETYPEWRITERS Filed April 12, 1951 "LETTERS" (wvsu/Ffl FRAME /N l/E N TOR D. E. BRA/VS ON Patented June 30, 1953 KEYBOARD MECHANISM FOR TELETYPEWRITERS David E. Eranson, Morristown, N. J., assignor to Bell'ielephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application April 12, 1951, Serial No. 220,564

1 1 Claim.

This invention relates to printing telegraph apparatus and more particularly to a keyboard mechanism in which a plurality of keys are arranged to position a set of permutation elements in different combinations. Such keyboards are employed principally in telegraph systems for transmitting signals to a receiving printer or in a perforator unit wherin tape is perforated in accordance with a code made up of permutations of different numbers of two different conditions.

The keyboard mechanism of the present invention is particularly adapted for use in a teletypewriter at a station in a system wherein the transmission of a message from the station to one or more receiving printers at a remotely lo cated station or stations involves the automatic transmission of certain codes, such address code signals, end-of-address signals and end-of-message signals, and the like. The end-of-message signal, which consists of a combination of figures, H and letters signals, requires a distinction to be made between transmitting the.

character signal for the letter H in combination with the figures signal and transmitting the letter H alone, such as when transmitted as a part of the message.

An object of the present invention is to prevent sending a signal consisting of the figures and H permutation code combinations from a teletypewriter keyboard in a teletypewriter system equipped with arrangements for automatically transmitting figures H signal code combinations.

According to the present invention, the teletypewriter keyboard is modified to prevent the operation of the H character key lever while the teletypewriter is in its shift or upper case condition, to which it is operated in response to the operation of the figures key lever. The modification consists in attaching a bar of metal or other suitably rigid material to the underside of the teletypewriter framework and immediately to the rear of the key lever guide, or comb, and having pivotally mounted thereon three bars with camming surfaces respectively arranged in engageable relation with the underside of three key levers, namely, those of space, figures (shift), and letters (unshift) keys, and a blocking bar in engageable relation with the H key lever. Two of the camming bars, the space camming bar excluded, and the blocking bar for the key lever are pivotally connected to a link rod of suitable material so that the movement of any one of the three bars in either a clockwise or a counter-clockwise direction causes the other two bars to simultaneously move in the same direction. Should the teletypewriter be in its unshift position at the time the figures key lever is operated, the figures carnming bar would move in a counter-clockwise direction and should it be in its shift position at the time the letters key lever is operated the letters camming barwould move in a clockwise direction. The H blocking bar depends for its movement upon the operation of either the figures or 1etters,camming bar. The H blocking bar upon moving in a counterclockwise direction in response to the operation of the figures key lever through the medium of the link rod, prevents the operation of the "51 key lever, and upon moving in a clockwise direction in response to the operation of either the letters or the space camming bar permits the operation of the H key lever, the space camming bar being detachably juxtaposed to the figures camming bar so that the space camming bar upon being moved in a clockwise direction will move the other camming bars in the same direction if it is in engagement at the time with the figures camming bar.

In view of the fact that many teletypewriters are so constructed that an automatic unshift of the platen is had in response to a space signal as well as the unshiit in response to a letters signal, the keyboard mechanism disclosed herein is arranged to be restored to its unshift condition, as regards the H key lever, in response to either of these signals.

A feature of the invention is the provision of means to avoid unintentional transmission of an end-of-message signal when sending a message in a teletypewriter private line intercommunicatin system equipped with automatic transmission arrangements for sending end-of-message, address, end-of-address, end-of-transmission and'the like.

Other objects and features Will be noted from the following description'taken in conjunction with the accompanying drawingswherein: Fig; 1 is a front elevation of a cross-sectional view of the key levers of a page type teletypewriter provided with camming bars in engageable rela tion with their respectively associated key levers; Fig. 2 shows a side elevation of Fig. 1 taken along line 2-2; and I Fig. 3 shows another side elevation of the arrangement shown in Fig. 1', taken along line 33. Referring to Fig. 1, bar i l of metal or some other suitably rigid material is fastened by means tail in United States Patent 1,904,164, granted to Morton-Krum-Kleinschmidt on April 18, 1933. The disclosure of this patent is hereby made a part of this disclosure as if fully included herein. Bar H is located immediate to the rear of the key lever guide, or comb (not shown), but provided with slots through which the keylevers extend to be in engageable relation with the code bars (not shown). Pivotally aflixed to the rear of. bar H are three camming bars, and a blocking bar, namely, space camming bar 14, figures camming bar l5, H blocking bar |S,-and letters camming bar H. The camming bars are so spaced that their top camming surfaces arein engageable relation with the underside of space key lever 18, figures key lever l9, and letters key lever 20, respectively. These key. leversare engaged at their rear ends by a pivot rod and each is upheld in a normal position by a spring, the pivot rod and spring corresponding to those respectively shown in Patent 1,90%,164. The forward upturned end of the key levers are provided with key tops 22 except the space key lever 18 which may be providedwith a-relatively long space bar 23 which is shown in front of key tops 22 inFigs. 2 and 3.

'Each of the cammingbars. l4, l and l! and also the blockingbar i6 is pivotally mounted by means of a machine screw 25 on metallic bar 51.

' Formed integrally onthe right-hand edge of camming bar M are two tangs 25. These tangs are in engageable relation with the left-hand edge of camming bar l5 and serve to move camming bar keylever l8. Pivotally mounted on each of carnming bars l5and I! as well as on blocking bar it by means of a machine screw 2! is a clamp 26,

the clamps 26 serving tosecurely support link rod 28. To reduce the lateral vibration of link rod 28 a supporting member 29 is fixedly attached to bar I l by means of machine screw 30, as shown in Fig. 3, there being sufiicient spring-like characteristic to member. 29 to. permit link rod. 28 to vmove freely with the movement of camming bars I5 and H.

The H blocking bar 16 is shown in its normal .or unshift position'wherein the H key lever 20 is free to operate .to cause the H character signal to be transmitted from the keyboard. When the figures key lever is operated its associated camming bar i5 is moved in a counterclockwise direction to its shift position thereby 'inoving blocking bar l6 and camming bar I? also in a'counter-clockwise direction to their shift positions, the shift position of blocking bar Hi being represented by bar i6 shown in dotted outline. It will be noted that the top surface of blocking bar l6 has integrally formed therewith a tang 32 which prevents key lever 28 from slipping olf the top surface of camming bar 16 should an attempt be made to operate key lever 20 at a time when blocking bar 16 is in its fshift" position.

In certain types of intercommunicating teletypewriter systems wherein code transmission arrangements are provided for automatically transmitting end-of-message signals and the like, independently of keyboard operations, it is highly desirable that means also be provided for preventing corresponding signals being inadvertently sent from the keyboard. In the particular case, at hand, the end-of-message signal which comprises the figures and H combination usually followed by some other code combination such as letters, is automatically transmitted at the end of aimessage by means not disclosed herein.

In order to avoid confusion with the automatic transmission of figures H code combinations the teletypewriter, used in a system wherein such signals are automatically transmitted, is modified in accordance with the present invention to provide mechanical locking means on its keyboard so that the operator cannot send, by means of the keyboard, figures and H code combinations in succession.

It isunderstood that the scope of the present invention is not limited to the specific arrangement shownin the drawing but that the principle may be employedwherever it is desirable to prevent the transmission of certainv signal combinations directly from the'keyboard.

'What is claimed is:

In a keyboard controlled telegraph transmitter, a plurality of individually depressible key levers including one assignedto control the. generation of an upper case shift signal, one to control the generation of a lower case shift signal, one to control the generation of a character spacing signal, and a plurality to control thegeneration of character signals, an arm pivotally mounted below said upper case shift key lever and'having a camming surface presented in the path of. that key lever to cause pivotalmovement of said arm in one direction by that key lever, a similar arm associated with said lower case shift. key leverand having its camming surface arranged to cause pivotal movement of the arm in the opposite direction, a link member interconnecting said arms for longitudinal movement by either of them and of such length that either arnrupon being pivotally operated by its associated key lever, rcstores theotherarm, a key lever blocking ei'emerit associated with said link member for blocking and alternately unblocking one of said charac ter signal key levers accordingto the movement of said link member by the respective arms, and another pivotally mounted arm presenting a camming surface in the path of said spacing key lever and operable to move saidlink member in. the same directionasthe arm associated with said lower case shift. keylever.

' DAVID; E. BRANSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,814,236 Wusteney July 14, 1931 2,115,185 Weber Aug. 26, 1938 V =FOREIGN PATENTS Number Country Date 860,231 France ept. 24, 1940 

